Hydraulic system of work machine

Patent metadata

Field	Value
Publication number	US-10451094-B2
Application number	US-201615278107-A
Country	US
Kind code	B2
Filing date	Sep 28, 2016
Priority date	Sep 28, 2015
Publication date	Oct 22, 2019
Grant date	Oct 22, 2019

Abstract

A hydraulic system of a work machine includes a first oil path which is connected to a hydraulic pump and though which hydraulic oil is to flow from the hydraulic pump. An operation valve is connected to the first oil path. An operation lever is to control the operation valve to control pressure of the hydraulic oil in accordance with an operation of the operation member. A hydraulic instrument is to be actuated by the hydraulic oil output from the operation valve. A second oil path connects the operation valve and the hydraulic instrument. The hydraulic oil in the second oil path is discharged through a discharge oil path. An actuation valve is provided in the discharge oil path. An actuation valve controller is to control the actuation valve to be opened and closed according to a temperature of hydraulic oil detected by a first sensor.

First claim

What is claimed is:

1. A hydraulic system of a work machine, comprising:
a hydraulic pump to discharge hydraulic oil;
a drive device to generate power to actuate the hydraulic pump;
a first sensor to detect temperature of the hydraulic oil;
a first oil path which is connected to the hydraulic pump and though which the hydraulic oil is to flow from the hydraulic pump;
an operation valve connected to the first oil path;
an operation lever to control the operation valve to control pressure of the hydraulic oil in accordance with an operation of the operation lever;
a hydraulic instrument to be actuated by the hydraulic oil output from the operation valve;
a second oil path connecting the operation valve and the hydraulic instrument;
a discharge oil path through which the hydraulic oil in the second oil path is discharged;
an actuation valve provided in the discharge oil path; and
an actuation valve controller to control the actuation valve to be opened and closed according to the temperature of the hydraulic oil detected by the first sensor,
wherein a throttle is provided between the operation valve and a connection of the second oil path and the discharge oil path.

2. The hydraulic system according to claim 1 , wherein the actuation valve is opened when the temperature of hydraulic oil detected by the first sensor is equal to or lower than a temperature threshold.

3. A hydraulic system of a work machine, comprising:
a hydraulic pump to discharge hydraulic oil;
a drive device to generate power to actuate the hydraulic pump;
a first sensor to detect temperature of the hydraulic oil;
a second sensor to measure temperature of air external to the work machine;
a first oil path which is connected to the hydraulic pump and though which the hydraulic oil is to flow from the hydraulic pump;
an operation valve connected to the first oil path;
an operation lever to control the operation valve to control pressure of the hydraulic oil in accordance with an operation of the operation lever;
a hydraulic instrument to be actuated by the hydraulic oil output from the operation valve;
a second oil path connecting the operation valve and the hydraulic instrument;
a discharge oil path through which the hydraulic oil in the second oil path is discharged;
an actuation valve provided in the discharge oil path; and
an actuation valve controller to control the actuation valve to be opened and closed according to the temperature of the hydraulic oil detected by the first sensor,
wherein the actuation valve is opened when the temperature of the hydraulic oil is equal to or lower than a first temperature threshold and the temperature of the air measured by the second sensor is equal to or lower than a second temperature threshold.

4. A hydraulic system of a work machine, comprising:
a hydraulic pump to discharge hydraulic oil;
a first oil path connected to the hydraulic pump;
an operation valve provided in the first oil path;
an operation lever to control the operation valve to control pressure of the hydraulic oil in accordance with an operation of the operation lever;
a hydraulic instrument to be actuated by the hydraulic oil output from the operation valve;
a second oil path connecting the operation valve and the hydraulic instrument;
an actuation valve provided in the first oil path between the operation valve and the hydraulic pump, the first oil path having a first section between the operation valve and the actuation valve;
a third oil path connecting the first section and the second oil path; and
a check valve provided in the third oil path, the hydraulic oil being configured to flow from the second oil path to the first oil path via the check valve, the hydraulic oil being prevented from flowing from the first oil path to the second oil path via the check valve.

5. The hydraulic system according to claim 4 , wherein a throttle is provided in the second oil path between the operation valve and a connection of the second oil path and the third oil path.

6. A hydraulic system of a work machine, comprising:
an operation lever operable in a first direction and a second direction orthogonal to the first direction;
a hydraulic pump to discharge hydraulic oil;
a first oil path connected to the hydraulic pump;
a first operation valve connected to the first oil path, the operation lever being configured to control the first operation valve to control pressure of the hydraulic oil in accordance with an operation of the operation lever in the first direction to output a first pressure of the hydraulic oil;
a second operation valve connected to the first oil path, the operation lever being configured to control the second operation valve to control pressure of the hydraulic oil in accordance with an operation of the operation lever in the second direction to output a second pressure of the hydraulic oil;
a third operation valve connected to the first oil path, the operation lever being configured to control the third operation valve to control pressure of the hydraulic oil in accordance with an operation of the operation lever in a third direction opposite to the first direction to output a third pressure of the hydraulic oil;
a fourth operation valve connected to the first oil path, the operation lever being configured to control the fourth operation valve to control pressure of the hydraulic oil in accordance with an operation of the operation lever in a fourth direction opposite to the second direction to output a fourth pressure of the hydraulic oil;
a hydraulic instrument to be actuated by the hydraulic oil output from at least one of the first operation valve, the second operation valve, the third operation valve, and the fourth operation valve, the hydraulic instrument being a travel device to travel forward, backward, rightward, and leftward, the first operation valve being configured to output the hydraulic oil for forward travel to the travel device, the third operation valve being configured to output the hydraulic oil for backward travel to the travel device, the second operation valve being configured to output the hydraulic oil for rightward travel to the travel device, and the fourth operation valve being configured to output the hydraulic oil for leftward travel to the travel device; and
an oil pressure changing circuit configured:
to change pressure of the hydraulic oil acting on the hydraulic instrument from the first operation valve from the first pressure when the operation lever is operated both in the first direction and in the second direction and to change pressure of the hydraulic oil acting on the hydraulic instrument from the second operation valve from the second pressure when the operation lever is operated both in the first direction and in the second direction;
to change pressure of the hydraulic oil acting on the hydraulic instrument from the second operation valve from the second pressure when the operation lever is operated both in the third direction and in the second direction and to change pressure of the hydraulic oil acting on the hydraulic instrument from the third operation valve from the third pressure when the operation lever is operated both in the third direction and in the second direction;
to change pressure of the hydraulic oil acting on the hydraulic instrument from the first operation valve from the first pressure when the operation lever is operated both in the first direction and in the fourth direction and to change pressure of the hydraulic oil acting on the hydraulic instrument from the fourth operation valve from the fourth pressure when the operation lever is operated both in the first direction and in the fourth direction; and
to change pressure of the hydraulic oil acting on the hydraulic instrument from the third op

Assignees

• Kubota Kk

Inventors

• Fukuda Yuji
• Arii Kazuyoshi
• Sumiyoshi Ryohei

Classifications

• F15B2211/3052

  Shuttle valves · CPC title

• F15B2211/50518

  using pressure relief valves · CPC title

• F15B2211/613

  Feeding circuits · CPC title

• F15B2211/20576

  with multiple pumps · CPC title

• F15B2211/324

  manually, e.g. by using a lever or pedal · CPC title